Elevated concentrations of Pb, a known neurocognitive toxin, have been found in traditional Indian eye cosmetics such as kohl, surma, and kajal. Children who use traditional eye cosmetics have also been found to exhibit elevated blood lead levels (BLL > 10 µg/dL) compared to children who do not use eye cosmetics (mean BLL 4.3 µg/dL). This suggests that Pb contained in culture-specific eye cosmetics is bioaccessible. Animal studies have found that oral ingestion of the cosmetics material is the primary route of lead exposure rather than transcorneal transport. However, there is a possibility that some of the material may be washed into the nasolachrymal duct during lacrimal fluid formation. This study quantifies the bioaccessibility of Pb from Indian eye cosmetics in lacrimal fluid.

XRF analyses of traditional eye cosmetic samples (kajal and surma) indicate [Pb] ranging from 1.1 µg/g to 177,700 µg/g. 92.3% of the samples contain [Pb] > 0.5 µg/g, the FDA action level for products intended for use by children and infants. Samples were selected for sequential extraction in unbuffered saline solution based on PCA clustering. ICP-OES analysis of each sequential extraction indicated leaching of Pb and Zn in all samples, suggesting lacrimal fluid transport as a potential pathway of lead exposure. After 60 hours of incubation, extractable [Pb] and [Zn] were 0.0011% and 0.10%, respectively, of bulk [Pb] and [Zn] in untreated high [Pb] samples (177,700 µg/g). Further XRD analysis and SEM imaging indicates galena (PbS) and zincite (ZnO) as the major crystalline metal phases of these high [Pb] samples. The low Ksp of galena (3.4 x 10-28) and zincite (5.9 x 10-12) may account for the low bioaccessibility of Pb and Zn in high [Pb] samples. However, extractable [Pb] and [Zn] range from 9.7% to 104.6% in low [Pb] kajal samples (< 100 µg/g) after 60 hours of incubation, suggesting more bioaccessible forms of Pb and Zn in these samples. Overall, variable Pb and Zn bioaccessibility exists between different kajal samples. Further bioaccessibility assessment of Pb and Zn for traditional Indian eye cosmetics is important to understanding non-traditional exposure pathways of trace elements of interest as well as the public health implications of traditional Indian eye cosmetic usage.